Aegisuchus
The holotype of Aegisuchus witmeri, a skull fragment in different views
- Kem Kem Formation, North Africa
- Aegisuchus witmeri Holliday & Gardner, 2012
Aegisuchus witmeri is an extinct species of archosaurs. The only known member of the genus Aegisuchus was a huge Krodilverwandter with flat head, strong jaw and head shield. It lived during the Late Cretaceous in the area of present-day Morocco in a marshy area where it may be fed on fish.
Aegisuchus witmeri was first described in 2012 by Casey Holliday and Nicholas Gardner. Together with the genus Aegyptosuchus Aegisuchus is placed in the Aegyptosuchidae family, the sister group of crocodiles ( Crocodilia ). The presence of Aegisuchus fossils in the Upper Cretaceous of North Africa presents hypotheses in question, after which the modern crocodiles have evolved in Laurasia.
Features
Aegisuchus was a huge crocodile relative with an estimated body length of about 15 m. The length of the skull was from 2.1 to 2.9 m. The underlying model calculations Aegisuchus was not only larger than Purussaurus, Sarcosaurus or Deinosuchus, it had a volume of 40 cc and the largest brain of any known species. Because the estimated length is based on the volume of the brain, but it is also possible that Aegisuchus was less than expected, and only had a disproportionately large brain.
At the back of his head Aegisuchus had a head plate with wrinkled surface, which consisted of greatly thickened skin. He made the neck a transition to the back and pointed laterally two finger-like projections on. Its function is suspected in Balzritualen and exhibition battles. Muzzle and skull were strongly flattened; Aegisuchus probably had a very flat upper jaw, reminiscent in shape to the beak of ducks. The eyes did not have any beads, but lay flat in the skull. Due to the shape of the head and snout, the animals had a relatively strong jaw and neck muscles. They allowed Aegisuchus relatively generous head movements.
Distribution and stratigraphy
Aegisuchus has been found exclusively in the North African Kem Kem Formation in south-eastern Morocco. The formation dates from the Upper Cretaceous Cenomanian; the layer was found in the Aegisuchus, has an age of 93-98 million years ago.
Ecology
The habitat of Aegisuchus was a vast marshland along a river. The waters and the adjacent regions were inhabited by numerous species of fish, amphibians and reptiles such as plesiosaurs larger, theropods and sauropods. As with the morphologically similar genera Laganosuchus and Stomatosuchus is also suspected of Aegisuchus that they are predominantly fed on sluggish fish such as coelacanth, lungfish or Flösselhechten. Land vertebrates could have also been identified as occasional prey part of the food.
System
The genus Aegisuchus was erected in 2012 by Casey Holliday and Nicholas Gardner A. witmeri the only way. The holotype (ROM 54530 ), a partially -preserved cranium, was found commercial fossil collectors in the Kem Kem Formation and sold to the Royal Ontario Museum in Toronto. Holliday and Gardner chose the generic name ( aegis, Greek for shield; souchus, Greek for crocodile ) according to the head of the animal sign. The specific epithet honors Lawrence M. Witmer for his contribution to the study of the cranial anatomy of archosaurs.
The two authors assigned Aegisuchus because of its head shield as a sister taxon of the genus also cenomanischen Aegyptosuchus from Egyptian Bahariija lineup. Both genera together form the family Aegyptosauridae, an assessment that was supported by a morphological analysis of 45 Crocodyliformes taxa. Thus Aegisuchus and Aegyptosuchus together form the sister group to the modern crocodiles ( Crocodilia ). The existence of such a modern group of crocodile relatives contradicts hypotheses that (now North America ) start from a recent emergence of crocodiles in Western Laurasia. Instead, they leave a Radiation in the area of the Tethys Sea plausible.